Course 108 Unit 4.2 Operating ABG and Co Ox analyzers Flashcards
What is a sanz electrode?
- measures pH
- measurements are made by comparisons
- comparison between a solution of known pH (reference electrode) and a solution of unknown pH (blood)
- two solutions are separated by pH sensitive glass membrane
- electrical potential across membrane read as pH
- requires buffer for calibration (2 standards are required and must be in physiologic range)
What is ABG analysis?
Functional operation of blood gas electrodes
What is an anode?
positive pole (Ag/ AgCl)
What is a Cathode?
negative pole (Platinum)
What is oxidation?
a loss of an electron by a particle
What is reduction?
a gain of electrons by a particle
What is Severinghaus electrode?
- measures PCO2
- based on Henry’s Law (states the amount of gas diffusing across the membrane is directly proportional to the pressure gradient
- as blood passes through the semi permeable membrane CO2 diffuses across and reacts chemically with the aqueous bicarbonate solution on the other side
- -hydrogen ion concentration developed is directly proportional to the PCO2 in contact with the membrane
What is a Clark electrode?
- measures PO2
- made of silver anode immersed in a KCl electrolyte solution (oxidation occurs between the anode and KCl creating free electrons (e-)
- an adjacent platinum cathode will react with O2 and H2O utilizing the electrons (reduction)
- results in a flow of current between the anode and the cathode
- an increase in O2 concentration will the current
- measuring the change in current (electron flow) between the anode and cathode, the amount of O2 in the electrode solution can be determined
What are the procedures for ABG analysis?
- Obtain sample: wear protective gloves any time you are dealing with blood or bodily fluids * in case of an accidental needle stick or any other possible type of contamination notify your NCOIC and or shift leader immediately
- Ensure all air bubbles have been removed from the syringe
- Mix sample thoroughly: roll between hands, especially if sample has been stored for more than a few minutes
- Introduce sample into analyzer
- Watch for air bubbles and clots as sample run through analyzer
- Print/ record and report results IOW local policy
- Check results for errors: if results seem inaccurate run sample through another analyzer and compare results; if another analyzer isn’t available place sample on ice then run control through analyzer to check for accuracy (do results appear how they should for blood and oxygenation level
Can temperature be corrected for ABG analysis?
yes, results can be corrected if patient temp is other than 37 degrees C or 96.6 degrees F
What makes a spectrophotometric oximeter operate?
Spectrophotometry:
- Spectro: spectrum
- Photo: light
- Metry: measurement
- light is transmitted at specific wavelengths, passes through the substance being analyzed (blood) by a photo detector on the opposite side: Light transmission will either be:
- absorbed (optical density)
- pass through (inverse to light absorbed)
- be reflected (backscatter oximetry)
What is the light absorption principle?
Lambert-Beer Law: determines hemoglobin saturation/ concentration (each Hb has its own unique absorption/transmission spectrum)
How many wavelengths does co-oximetry use?
uses eight light wavelengths to differentiate hemogloblin species
- HbO2 (oxygenated Hb)
- Hb (deoxygenated
- MetHb (Met-hemoglobin Fe 3+)
- HbOC (carboxyhemoglobin)
- HbO2 (oxygenated Hb)
What is an isobestic point?
where 2 Hb species absorb light equally at a given wavelength (also known as common points)
What are the different co-oximetry measurements?
- total Hb: tHb (g/dl)
- oxyhemoglobin saturation (SpO2= functional SaO2)
- oximetry via 2 wavelength spectrophotometers
- HbCO and MetHb are excluded= non functional Hb (deoxygenated Hb) - oxihemoglobin sat (SaO2 (fractional SaO2= disfunctional Hb)
- carboxyhemoglobin HbCO (smoke inhalation): normal range; 1.5 to 9.0 percent of tHb
- met-hemoglobin met-Hb (INO and Hurricane tropical anesthetic and others): normal is 1 percent or less
- sulfhemoglobin HbS (sickle cell anemia)